An X-ray radiation detector is known from U.S. Pat. No. 7,652,258 B2.
In imaging systems, such as for example computer tomographs, directly converting detectors are increasingly employed for the detection of X-ray radiation, in which the radiation to be detected is converted directly into an electrical measuring signal in a semiconductor layer composed for example of CdTe, CdZnTe, CdZnTeSe, CdTeSe, CdMnTe, InP, TIBr2 or HgI2.
Typical of semiconductor materials of this kind is a relatively high concentration of lattice defects, which inter alia are electrically effective as so-called “traps” for electrons. As a rule, many of the energy levels belonging to these impurities are unoccupied under normal conditions, and are occupied only upon irradiation of the semiconductor with X-ray radiation. The electrons occupying these energy levels are subsequently bound to the defect and thus remain permanently fixed in the semiconductor crystal, giving rise to a radiation-dependent polarization of the semiconductor crystal. A falsification of the measuring signal results from this, firstly because some of the free charge carriers generated by the radiation to be detected no longer contribute to the measuring signal, but are in part captured by the impurities, and secondly because the electrical displacement field having an effect in the semiconductor material changes as a result of the fixed charges.
In patent U.S. Pat. No. 7,652,258 B2, it is proposed to irradiate the detector with infrared radiation, in order thus to prescribe an occupation of the impurity levels and thus to prescribe the polarization status with the aid of the infrared radiation. The infrared radiation is hereby generated in a laborious manner in an additional infrared generator and coupled into the detector structure.